package com.hdu.pool;

import java.sql.*;
import java.util.Collections;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executor;
import java.util.concurrent.atomic.AtomicIntegerArray;

/**
 * 连接池
 */
public class Pool {

    private static final int BUSY = 1;
    private static final int FREE = 0;


    /**
     * 连接池大小
     */
    private final int poolSize;

    /**
     * 连接池
     */
    private final Connection[] connections;

    /**
     * 连接状态
     */
    private final AtomicIntegerArray status;

    public Pool(int poolSize) {
        this.poolSize = poolSize;
        this.connections = new Connection[poolSize];
        for (int i = 0; i < poolSize; i++) {
            connections[i] = mockConnection();
        }
        this.status = new AtomicIntegerArray(poolSize);
    }

    public Connection getConnection() {
        while (true) {
            for (int i = 0; i < poolSize; i++) {
                if (status.compareAndSet(i, FREE, BUSY)) {
                    return connections[i];
                }
            }
            synchronized (this) {
                try {
                    this.wait();
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
            }
        }
    }

    public void resetConnection(Connection connection) {
        for (int i = 0; i < poolSize; i++) {
            if (connections[i] == connection) {
                if (status.compareAndSet(i, BUSY, FREE)) {
                    synchronized (this) {
                        this.notifyAll();
                    }
                    return;
                }
            }
        }
    }


    private Connection mockConnection() {
        return new Connection() {
            @Override
            public <T> T unwrap(Class<T> iface) throws SQLException {
                return null;
            }

            @Override
            public boolean isWrapperFor(Class<?> iface) throws SQLException {
                return false;
            }

            @Override
            public Statement createStatement() throws SQLException {
                return null;
            }

            @Override
            public PreparedStatement prepareStatement(String sql) throws SQLException {
                return null;
            }

            @Override
            public CallableStatement prepareCall(String sql) throws SQLException {
                return null;
            }

            @Override
            public String nativeSQL(String sql) throws SQLException {
                return "";
            }

            @Override
            public void setAutoCommit(boolean autoCommit) throws SQLException {

            }

            @Override
            public boolean getAutoCommit() throws SQLException {
                return false;
            }

            @Override
            public void commit() throws SQLException {

            }

            @Override
            public void rollback() throws SQLException {

            }

            @Override
            public void close() throws SQLException {

            }

            @Override
            public boolean isClosed() throws SQLException {
                return false;
            }

            @Override
            public DatabaseMetaData getMetaData() throws SQLException {
                return null;
            }

            @Override
            public void setReadOnly(boolean readOnly) throws SQLException {

            }

            @Override
            public boolean isReadOnly() throws SQLException {
                return false;
            }

            @Override
            public void setCatalog(String catalog) throws SQLException {

            }

            @Override
            public String getCatalog() throws SQLException {
                return "";
            }

            @Override
            public void setTransactionIsolation(int level) throws SQLException {

            }

            @Override
            public int getTransactionIsolation() throws SQLException {
                return 0;
            }

            @Override
            public SQLWarning getWarnings() throws SQLException {
                return null;
            }

            @Override
            public void clearWarnings() throws SQLException {

            }

            @Override
            public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {
                return null;
            }

            @Override
            public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
                return null;
            }

            @Override
            public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
                return null;
            }

            @Override
            public Map<String, Class<?>> getTypeMap() throws SQLException {
                return Collections.emptyMap();
            }

            @Override
            public void setTypeMap(Map<String, Class<?>> map) throws SQLException {

            }

            @Override
            public void setHoldability(int holdability) throws SQLException {

            }

            @Override
            public int getHoldability() throws SQLException {
                return 0;
            }

            @Override
            public Savepoint setSavepoint() throws SQLException {
                return null;
            }

            @Override
            public Savepoint setSavepoint(String name) throws SQLException {
                return null;
            }

            @Override
            public void rollback(Savepoint savepoint) throws SQLException {

            }

            @Override
            public void releaseSavepoint(Savepoint savepoint) throws SQLException {

            }

            @Override
            public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
                return null;
            }

            @Override
            public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
                return null;
            }

            @Override
            public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
                return null;
            }

            @Override
            public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {
                return null;
            }

            @Override
            public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {
                return null;
            }

            @Override
            public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {
                return null;
            }

            @Override
            public Clob createClob() throws SQLException {
                return null;
            }

            @Override
            public Blob createBlob() throws SQLException {
                return null;
            }

            @Override
            public NClob createNClob() throws SQLException {
                return null;
            }

            @Override
            public SQLXML createSQLXML() throws SQLException {
                return null;
            }

            @Override
            public boolean isValid(int timeout) throws SQLException {
                return false;
            }

            @Override
            public void setClientInfo(String name, String value) throws SQLClientInfoException {

            }

            @Override
            public void setClientInfo(Properties properties) throws SQLClientInfoException {

            }

            @Override
            public String getClientInfo(String name) throws SQLException {
                return "";
            }

            @Override
            public Properties getClientInfo() throws SQLException {
                return null;
            }

            @Override
            public Array createArrayOf(String typeName, Object[] elements) throws SQLException {
                return null;
            }

            @Override
            public Struct createStruct(String typeName, Object[] attributes) throws SQLException {
                return null;
            }

            @Override
            public void setSchema(String schema) throws SQLException {

            }

            @Override
            public String getSchema() throws SQLException {
                return "";
            }

            @Override
            public void abort(Executor executor) throws SQLException {

            }

            @Override
            public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException {

            }

            @Override
            public int getNetworkTimeout() throws SQLException {
                return 0;
            }
        };
    }
}

